The invention relates to a vehicle tyre having a non-uniformly profiled tread with respect to its centre.
In the design of the tread pattern of vehicle tyres an attempt must always be made to take account of a plurality of partly mutually contradicting requirements, such as for example the aquaplaning or hydroplaning behaviour, the tread wear, the noise generation, the handling characteristics and the like.
It is known to design the tread patterns with broad grooves to improve the aquaplaning behaviour, in particular with a very broad groove at the centre of the tread or with two comparatively broad grooves on both sides of the centre of the tread. These known tread designs are, however, associated with the disadvantage that the improvement of the aquaplaning or hydroplaning behaviour, associated with the broadening of the circumferential grooves, leads to a deterioration of characteristics which are important in the same manner for the assessment of the relevant tyre, such as above all the handling and the noise generation and/or the passing noise.
The object of the invention is to so design the tread of a vehicle tyre while generally ensuring good handling characteristics that at a the same time provide a very good aquaplaning or hydroplaning behaviour and low passing or passing-by noise.
According to the invention there is provided a vehicle tyre having a non-uniformly profiled tread with respect to its centre, characterised in that one tread half, in particular the inwardly disposed tread half related to the vehicle, has at least one circumferential superwide groove having a width of at least 30 mm and the other tread half, in particular the outwardly disposed tread half, has at least two narrower grooves in comparison thereto which likewise extend over the tyre circumference, with the superwide groove being at least twice as broad as the broadest of the narrower grooves.
Through the combination of a super-wide circumferential groove disposed in one half of the tyre tread with at least two narrower grooves in comparison thereto which are disposed in the other tread half, one succeeds, in surprising manner, in ensuring a good aquaplaning behaviour with a low passing noise, in particular avoiding the feared so-called organpipe noise when using circumferential grooves, i.e. the occurrence of resonant frequencies in the 1 kHz range.
The width of the superwide groove preferably amounts to at least approximately 30 mm and in particular to more than 35 mm, whereas the narrower grooves have a width of 15 mm or less, more preferably 10 mm and less.
Extensive freedom exists with respect to the tread design using grooves and fine cuts or sipes in the raised tread surface regions between and to the side of the circumferential grooves. Grooves extending obliquely with respect to the circumferential plane of the tyre, are, however, preferably used in order to avoid the striking of edges of the grooves in the tread contact patch. Fine cuts or lamella cuts can, however, also be provided extending in the transverse direction.
In the overall design of the tread pattern, attention should be paid to the fact that the positive component of the tread in the outer region is larger than in the inner region with respect to the vehicle in order to take account of the handling behaviour.
In accordance with a preferred embodiment of the invention, at least the narrower circumferential grooves are connected to one another by continuously curved grooves which extend obliquely with respect to the central plane of the tyre and which preferably extend from the tyre shoulder up to and into the vicinity of the superwide groove, with their inclination relative to the circumferential direction decreasing towards the tyre shoulder.